Shamorie Ponds pumped his fist. Marcus Lovett Jr. outstretched his arm, circling the court at a sprint and high-fiving anyone who would accept his hand following St. John’s electric, stunning 76-73 win over No. 13 Butler on Thursday in both teams’ Big East opener.

The party was hopping, as were the 5,602 fans at a sold-out Carnesecca Arena and, amid the joyous chaos, Chris Mullin, with an almost reluctant smile, looked tired.

“It’s a legitimate process,” the second-year coach said after his biggest coaching win, in a season in which there have been whispers about the team not coming together under his command. “Certain days you’re gonna have a headache or you don’t sleep well. But part of the process is dealing with those emotions, the ups and downs, being able to focus.”

St. John’s focused down the stretch, turning a 65-58 deficit with 7:36 left into a hectic victory, jump-started by a full-court press that rattled the experience-laden Bulldogs (11-2, 0-1 Big East). The Red Storm turned up the pace and came up with six turnovers over the final 11:03 from a Butler team that looked skittish.

Ponds, the star freshman guard, led the way with 26 points, 11 coming in the final 11 minutes, as St. John’s (7-7, 1-0) got its second straight stunning victory, following a destruction of Syracuse at the Carrier Dome on Dec. 21.

“[Beating Syracuse] definitely gave us confidence,” junior swingman Bashir Ahmed said after his 19-point performance. “We just wanted to go out there and just fight hard. I feel like we did that today.”

It was a fight until the very end. To seal their most impressive on-campus win since beating No. 13 Syracuse in February 1983 — a game in which Mullin poured in 19 points — the Johnnies had to first overcome Butler, then hold off a few last-second scares.

Down three with six seconds left, Butler threw a football heave to forward Andrew Chrabascz, who missed the potential game-tying 3-pointer.

St. John’s coach Chris MullinAnthony J. Causi

Johnnies senior forward Darien Williams did not let Red Storm fans breathe easily, missing both free throws with 1.3 seconds left, and a prayer by Butler junior forward Kelan Martin went off the front rim as the buzzer sounded.

For a team that has lost, inconceivably, to Delaware State and LIU Brooklyn, as well as handily to Penn State, Ponds sounded like a member of a No. 13-ranked squad, not a team that knocked one off.

“They’re a good team, and the second half we just cut down on the mistakes and got the win,” the Brooklyn product said after the Red Storm’s 16-turnover performance in a surprisingly fast-paced game, with seven coming in the second half. “We just tried to stay together, stay poised. They took the [nine]-point lead [with 11 minutes left], we just stayed together.

“We needed this one a lot. We felt like if we just come out and compete, we’re unstoppable.”

Mullin would not go that far when talking about his youthful team, but he sounded relieved about a 1-0 Big East record a season after a 1-17 conference record.

“You learn a lot … from the losses that we have, we get experience,” Mullin said. “And the only way you get experience is going through this.”

Forward Amar Alibegovic (knee) returned after missing the previous three games, playing seven minutes without scoring. Sharpshooter Federico Mussini (infection) missed a second straight game.